This application claims priority under 35 U.S.C. xc2xa7xc2xa7 119 and/or 365 to Appln. No.00810112.3 filed in Europe on Feb. 9, 2000; the entire content of which is hereby incorporated by reference.
The invention relates to a steam condenser in a steam power installation or combined installation, which steam condenser is arranged, with the turbine, at ground level and to which the turbine steam flows in the horizontal direction through a condenser neck. The steam condenser has a plurality of tube bundles, which have an elongated configuration, are supported horizontally and are separated from one another by a central passage via which the steam flows into the tube bundles. An appliance for the introduction of steam which is fed via a bypass conduit from the boiler of the power installation directly into the condenser is arranged at the condenser neck.
Such a steam condenser with horizontal steam inlet flow is, for example, described in EP 0 384 200. It has a plurality of bundles of tubes which have an elongated configuration, are arranged horizontally and through which the cooling water flows. The steam inlet flow from the turbine takes place in the horizontal direction via the condenser neck into the central passages and, from there, into the internal region of the tube bundles, where the steam condenses. The condensate forming on the tubes flows down over condensate collecting plates into a hotwell in the floor region of the condenser.
In practice, such a steam condenser is of modular construction, each module containing, for example, two tube bundles between which there is a free space or a central passage through which the steam can pass to the cooling tubes in the tube bundles. For space reasons, the modules are respectively arranged so that they lie one above the other, their central, horizontal module walls, which face an adjacent module, being connected to one another by assembly weld seams. The condensate which is produced in the tube bundles of the upper module flows to an opening at the bottom of each module. From there, it finally passes into the lower module and into the hotwell of the condenser.
Because of manufacturing tolerances, the welded connection between the central module walls involves the risk of a gap occurring along these module walls. In consequence, the contact surfaces are uneven at this location and uneven stresses occur. Particularly in the region of the drain opening for the condensate from the upper module to the lower module, these can lead to leaks and can introduce a corrosion risk. Because the module walls are located directly one above the other, it is impossible to inspect this corrosion visually and, if necessary, initiate a repair.
During the run-up and run-down of a power installation and during load rejection, steam from the boiler is supplied directly to the condenser via a steam bypass station. This is done for operational safety purposes and in order to reduce losses. Such a bypass station typically consists of two to three bypass conduits, which bypass the turbine, and a steam introduction appliance in the condenser neck. The mass flows through the bypass station are often larger than the turbine steam flow during normal turbine operation, particularly in the case of combined installations. Because the cross sections of the bypass conduits are much smaller than the cross section of the turbine exhaust steam connection, very strongly concentrated steam flows occur in the bypass conduits. In some cases, furthermore, the steam flows at supersonic velocity in the steam introduction appliance and this can lead to erosion damage to components in the condenser.
The space relationships at the condenser neck are limited, in some cases, because further installations also have to be located there. The pipework planning for the bypass conduits is therefore complicated and it is difficult to optimize the location of the introduction appliance at the condenser neck with respect to the flow dynamics.
In view of the prior art described here, the object of the invention is to create a steam condenser of modular construction, of the type described at the beginning, which avoids the disadvantages mentioned with respect to the connection of the modules.
The steam condenser modules arranged one above the other are, in accordance with the invention, separated from one another wherein a defined intermediate space exists between the adjacent modules, a plurality of connecting parts being arranged between the walls of the two modules which face one another.
Because of the distance between the modules provided by a defined intermediate space, the gap surfaces mentioned at the beginning and the associated risks of corrosion and stresses in the module walls are avoided. The intermediate space is expediently dimensioned in such a way that access for assembly operations and a visual inspection of the region of the module walls are made possible. Finally, the distance between the modules facilitates manufacture because both or all the modules can be identically manufactured and connected to one another by the connecting parts. In this arrangement, the number of weld seams necessary is also substantially reduced.
The connecting parts are used both for defining the space between the modules and for supporting the modules and, by this means, provide the advantage that the stress distribution in the central module walls is, as it were, defined. Furthermore, the stresses are no longer influenced by the manufacturing tolerances.
In addition, the adjacent modules are respectively connected by a connecting duct for the purpose of removing the condensate, which is produced in a module arranged above it and flows through a condensate drain opening in the bottom of each module into the module located underneath.
In a first embodiment example, the space between the modules is at atmospheric pressure. In an alternative embodiment example, the intermediate space is enclosed by side walls and is in connection, under vacuum, with the steam space. The first embodiment of the intermediate space at atmospheric pressure has the comparative advantage that the support of the modules requires fewer components and can therefore be realized in a simpler manner. The second embodiment, on the other hand, has the advantage that it permits simpler dewatering of the upper module without a plurality of individual connecting ducts.
In a preferred embodiment of the invention, the central, horizontally located module walls which face one another are arranged at a level such that they are located at the same level as the cylindrical walls of the water chambers. This arrangement advantageously contributes to the acceptance of the pressure forces from the water chambers. Bending moments, which otherwise occur due to the pressure from the water chambers on the central module walls, are avoided by this means. Ties or bracing ribs, which are otherwise necessary for accepting such bending moments, are no longer necessary, thus economizing in manufacturing and assembly costs.
In a further embodiment example of the invention, the connecting parts or straps have openings which can be used as transport suspension appliances.
In a further special embodiment, the intermediate space is used for locating bypass conduits. All the bypass conduits are preferably led from the same side of the condenser into the intermediate space and from there to a steam introduction appliance at the condenser neck. By this means, the intermediate space permits a greatly simplified conduit arrangement so that the conduits are shorter and similar flow relationships prevail in all conduits.
The steam introduction appliance is arranged at the level of the intermediate space. This has the advantage that the steam introduction appliance does not hinder the flow of turbine steam into the condenser because it is located in a xe2x80x9cdeadxe2x80x9d zone relative to this steam flow. The steam introduction appliance has a perforated bypass collecting conduit with a plurality of tube pieces, which bypass collecting conduit extends over the complete width of the condenser neck. A bypass conduit leads to each of these tube pieces. Each tube piece has, as perforation, a plurality of rows of openings or orifice drillings through which the bypass steam enters the condenser neck.
The perforated bypass collecting conduit is, on the one hand, arranged in the same direction as the cooling water tubes of the condenser and is, on the other hand, arranged at the level of the intermediate space where there are no cooling tubes. Behind it, therefore, there is only the intermediate space so that no negative vortices occur there which would hinder the flow of turbine steam to the cooling tubes.
The multi-row orifice drillings extending over the complete length of the bypass collecting conduit and, therefore, over the complete width of the condenser neck additionally provide the advantage that the bypass steam is expanded to such an extent that the risk of erosion by the bypass steam on components in the condenser and the condenser neck is reduced.